In aboveground storage tanks, corrosion of soil side bottoms and double bottoms is unpredictable and can reduce the thickness of the tank bottom up to about 5 mm/year. There are multiple tank bottom and foundation designs that address some of the corrosion problems. A typical corrosion protection method, i.e., cathodic protection system, in most cases is not effective due to inherent dry soil conditions at least during some part of a year. The use of soluble corrosion inhibitors, as with cathodic systems, is only viable in fully saturated sand or soil and it is generally difficult to obtain such saturated conditions. Protective coatings cannot be applied to existing or new tank soil side bottoms.
In summary, corrosion of aboveground storage tanks either with a single soil side bottom or a double bottom is a major worldwide problem. Such tanks face unpredictable application and environmental conditions that often cause the bottoms to leak. Polymer protection layers can be damaged or become water permeable over time and result in leaks of the stored product, which can lead to severe environmental impact requiring extensive cleanup activities along with environmental fines and other costs. Moreover, dangerous operating conditions occur when the leaking product is volatile or flammable. Another disadvantage is that repair of tank bottoms generally requires down time.